The invention relates to a support device for semi-trailers or the like, which is in particular height-adjustable. Such support devices are preferably arranged in pairs at the front of semi-trailers and expediently may be extended or retracted, i.e. adjusted between the support and the transport positions, and, in addition, they may be used for lifting the front area of the semi-trailer, insofar as this is required during hitching.
Support devices of the type in question are known from DE 196 16 704 A1 and DE 198 36 635 C5, for example. Here, in each case, a spindle nut of a lifting spindle drive is rigidly fastened to an extendible inner tube. In case there is a force or thrust on parked semi-trailers due to an air leak of the axle suspensions in the longitudinal direction of the vehicle or during loading or unloading in the lateral direction of the vehicle, for example, the support devices have to absorb also transverse forces in addition to the vertical load. This leads in particular to a bending load on the extended inner support tubes, the upper portions of which are located with guide clearance in the outer support tubes attached to the vehicle chassis. Here, there is the danger that the inner and outer tubes cant, which leads to bending so that, in the case of a rigid connection of the spindle nut and the inner support tube, the spindle may be bent, making the crank drive, which is usually provided, difficult to move, or making the support inoperative. U.S. Pat. No. 6,099,016 disclosed a support for a semi-trailer, where the spindle nut and the inner support tube are arranged mobile relative to one another and the spindle nut has a greater lateral movement clearance than the inner support tube so that it is prevented that the spindle bends. In this support, the supporting force will be absorbed by means of a plate attached below the spindle nut in the inner support tube.
Thus, the object underlying the present invention is to provide a support device, preferably for commercial vehicles such as semi-trailers, where the bending load on the spindle, in use, is reduced or prevented and which requires both less material and manufacturing outlay and which allows for simple mounting and dismounting.